1. Field of the Invention
This invention relates to a Centralized Management System utilizing a Bus Interface Unit, more particularly to a Centralized Management System that is capable of communicating a Computer Terminal with a First-Level Station through a dual port RAM (Random Access Memory), intercommunicating a plurality of Second-Level Stations through a Multipoint Interface and Multipoint Bus, and controlling and managing several thousands of Terminals (for example, Public Telephones) at a given time.
2. Background of the Invention
In general, Terminals that are connected to a Public Communication Network are installed at a number of sites which are distributed in a wide area and remote users control and manage the Terminals using a Central Computer. Recently, as Terminals become more widely utilized, an economical and efficient Management System is required.
FIG. 1 through 3 illustrate a System that manages the conventional Terminals.
FIG. 1 is a block diagram illustrating a Terminal Management System according to the first embodiment of the conventional method. As shown in FIG. 1, a Serial Communication Device 1u that is installed in a Computer 1z is connected to a Modem 1e and the Modem 1e is connected to the Terminal Device 1v by utilizing a Public Communication Network 1T.
Where a computer 1z communicates with Terminal Device 1v through the Serial Communication Device 1u that is installed in the Computer 1z, the number of Communication lines are limited to the number of Communication Devices that are installed in a Computer 1z, so that the number of Terminal Devices that can be connected at one time are limited. Moreover, a Computer 1z should wholly perform the control of the Serial Communication Device and Modem and communicating Communication protocols.
However, in case remote users control and manage the Terminal Devices that are connected to the Public communication Network and installed in multiple remote sites, the line capacity and performance of the Computer 1z deteriorate.
FIG. 2 is a block diagram illustrating a Terminal Management System according to the second embodiment of the conventional method. As shown in FIG. 2, a Serial Communication Device 2u is expanded by Bus Interfaces 2a, 2b, 2c of a Computer 2z and a Bus Interface 2x of a Serial Communication Controller 2d, in order to expand the Serial Communication Line of the Serial Communication Device 1u that is installed in the Computer 1z shown in FIG. 1. In such case, the expanded Serial Communication Device 2u comprises the Bus Interfaces 2a, 2b, 2c of the Computer 2z, Bus Interface 2x and Input/Output (I/O) Data and Control Signals 2y of the Serial Communication Controller 2d.
Moreover, the Serial Communication Device 2u is connected to a Modem 2e and communicates with Terminal Device 2v through a Public Communication Network 2T by the control of the Computer 2z. In this case, the Communication between the Serial Communication Device 2u and Terminal Device 2v follows the general Communication Protocols.
FIG. 3 is a block diagram illustrating M Serial Communication Devices 3u1, 3u2, . . . , 3uM which have been expanded using the method shown in FIG. 2 and a communication method of N Terminals 3v1, 3v2, . . . , 3vN performed through a Public Communication Network 3T. As shown in FIG. 3, each of M Ser. Communication Devices 3u1, 3u2, . . . , 3uM control each corresponding Serial Communication Device of M Serial Communication Devices 3u1, 3u2, . . . . , 3uM through Bus Interface Devices 3x1, 3x2, . . . , 3xM. Each of I/O Data and Control Signals 3y1, 3y2, . . . , 3yM of the Serial Communication Controller 3d1, 3d2, . . . , 3dM are connected to each of M Modems 3e1, 3e2, . . . , 3eM so that the Serial Communication Device 3u1, 3u2, . . . , 3uM communicate with N Terminal Devices 3v1, 3v2, . . . , 3vN through the Public Communication Network 3T. Moreover, the Communication between the Serial Communication Devices 3u1, 3u2, . . . , 3uM and Terminal Devices 3v1, 3v2, . . . , 3vN follows the general Communication protocols.
In this case, since the Computer 3z wholly performs the tasks for controlling Communications between the Serial Communication Devices 3u1, 3u2, . . . , 3uM and Modems 3e1, 3e2, . . . , 3eM through M Communication Lines, the capacity and performance of the Computer 3z deteriorate. Moreover, the number of Communication Lines that are installed in the system are limited, the Computer Programs for operating the Communication Lines are complicated, and remote users can not smoothly control and manage Terminal Devices 3v1, 3v2, . . . , 3vN through the Computer 3z due to load related to the control of the Communication Lines. Therefore, it is very difficult to build a system controlling and managing several thousands of Terminals according to the method shown in FIG. 3.